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    7.4 - Circumference Area Arc Length and Area of A Sector

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    James Tesen Garay
    Here are the steps to solve textbook problems 2-14 on page 411: 2) Find the circumference of a circle with diameter 20 ft. C = πd = π(20) = 20π ft 3) Find the circumference of a circle with radius 12 in. C = 2πr = 2π(12) = 24π in 4) Find the arc length of a 90° central angle with radius 8 m. Arc Length = (θ/360)2πr = (90/360)2π(8) = 3π m 5) Find the area of a circle with radius 15 cm. A = πr^2 = π(

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    7.4 - Circumference Area Arc Length and Area of A Sector

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    James Tesen Garay
    46 views25 pages
    Here are the steps to solve textbook problems 2-14 on page 411: 2) Find the circumference of a circle with diameter 20 ft. C = πd = π(20) = 20π ft 3) Find the circumference of a circle with radius 12 in. C = 2πr = 2π(12) = 24π in 4) Find the arc length of a 90° central angle with radius 8 m. Arc Length = (θ/360)2πr = (90/360)2π(8) = 3π m 5) Find the area of a circle with radius 15 cm. A = πr^2 = π(

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    7.4 - Circumference Area Arc Length and Area of a Sector

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    Here are the steps to solve textbook problems 2-14 on page 411: 2) Find the circumference of a circle with diameter 20 ft. C = πd = π(20) = 20π ft 3) Find the circumference of a circle with radius 12 in. C = 2πr = 2π(12) = 24π in 4) Find the arc length of a 90° central angle with radius 8 m. Arc Length = (θ/360)2πr = (90/360)2π(8) = 3π m 5) Find the area of a circle with radius 15 cm. A = πr^2 = π(

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    46 views25 pages

    7.4 - Circumference Area Arc Length and Area of A Sector

    Uploaded by

    James Tesen Garay
    Here are the steps to solve textbook problems 2-14 on page 411: 2) Find the circumference of a circle with diameter 20 ft. C = πd = π(20) = 20π ft 3) Find the circumference of a circle with radius 12 in. C = 2πr = 2π(12) = 24π in 4) Find the arc length of a 90° central angle with radius 8 m. Arc Length = (θ/360)2πr = (90/360)2π(8) = 3π m 5) Find the area of a circle with radius 15 cm. A = πr^2 = π(

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    of 25

    Warm up: Solve for x

    1.) 124◦ 2.) 70◦


    53 145
    x
    18◦
    x

    3.) 4.)
    260◦
    70
    80 x 20◦
    110◦

    x
    EOC REVIEW

    Question of the Day


    Questions over hw?
    Skills Check
    Circumference,
    Arc Length, Area,
    and Area of
    Sectors
    Circumference

    The distance
    around a circle
    Circumference
    Twinkle, Twinkle Little Star
    Circumference Equals 2 pi r

    C  2 r
    or

    C  d
    2 Types of Answers
    Rounded Exact
    • Type the Pi
    • Pi will be in
    button on your
    calculator your answer
    • Toggle your
    answer
    • Do NOT write Pi
    in your answer
    Find the EXACT circumference.

    1. r = 14 feet C  2 14 
    C  28 ft
    2. d = 15 miles
    C   15 
    C  15 m ile s
    Ex 3 and 4: Find the circumference.
    Round to the nearest tenths.

    C  2 14.3  C    33 

    C  89.8 m m C  103.7 yd
    Arc Length
    The distance along the curved line making the
    arc (NOT a degree amount)


    Arc Length
     measure of arc 
    Arc Length     2 r
     360 
    Ex 5. Find the Arc Length
    Round to the nearest hundredths
     measure of arc 
    Arc Length     2 r
     360 

     8m
     70 
    Arc Length    2 8  70
     360 

    Arc Le n g th = 9.7 7 m
    Ex 6. Find the exact Arc Length.
     measure of arc 
    Arc Length     2 r
     360 

     120  
    Arc Length    2 5 
     360 

    10
    Arc Le n g th =  in
    3
    Ex 7. What happens to the arc length if the
    radius were to be doubled? Halved?
     measure of arc 
    Arc Length     2 r
     360 


    20
    Do u b le d 
    3
    5
    Ha lve d 
    3
    Ex 8. Find the perimeter of the region.

    30  9 u n its
    Area of Circles
    The amount of space occupied.


    r
    A = pr 2
    Find the EXACT area.
    A    29 
    2
    8. r = 29 feet
    A  841 ft 2

    2
    9. d = 44 miles  44 
    A  
     2 
    A  484 m i 2
    10 and 11
    Find the area. Round to the nearest tenths.

    2
     53 
    A   7.6 
    2
    A  
     2 
    A  181.5 yd 2
    A  2206.2 c m 2
    Area of a Sector
    the region bounded by two radii of the circle and
    their intercepted arc.
    Area of a Sector
     measure of arc  2
    A    r
     360 
    Example 12 Find the area of the sector to the
    nearest hundredths.

    R
    cm  60 
     
    2
    6 60 A   6
    Q
     360 

    A  18.85 cm2
    Example 13 Find the exact area of the sector.

    6 cm

     120 
     7 
    7 cm 2
    R
    A 
    Q
     360 
    120

    49 
    A cm 2

    3
    Example 14 Area of minor segment =
    (Area of sector) – (Area of triangle)
      
     mRQ 2   1 
    R Area of minor segment = r   b  h
     360   2 
     
     90 2 1 
    Q =  (12)    (12)(12) 
    12 yd  360  2 

    =113.10  72
    2
    Area of minor segment =41.10 yd
    Textbook
    p. 411 #2 – 14

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